IMG_101@45X P. roseum plasmodium

Though amoeboid movement in Physarum is not unusual or uncommon, it is quite self evident, I was delighted to see it in progress other than the usual cytoplasmic streaming we see in the veinous cytoplasm normally. While intently observing P. roseum utilizing the dissecting microscope at 45X, I was delighted to see what appeared to be the membrane of one of the veins rupture in at least two places and the cytoplasm come rushing in to form up pseudopodia almost instantly. The hyaline membrane proceeding the infusion of the cytoplasm is clearly seen in the accompanying photograph along with some yet unidentified dark granules accompanying the pseudopodium (arrows) that were not present beforehand.

This could be what is referred to as "blebbing." https://en.wikipedia.org/wiki/Amoeboid_movement#Bleb-driven_motility